1. Field of the Invention
This invention relates to a method for correcting a position of a robot on the real time basis while detecting a target position on a workpiece by a laser sensor, and more particularly, to a method for controlling a robot such that the attitude of the robot may be always kept constant with respect to the object to be worked, by calculating the tool angle with respect to a sectional shape of the object to be worked or a direction of a row of points generated by laser scanning which is used primarily for detecting the target position detected for every laser scanning period.
2. Description of the Related Art
It is well known that a real time tracking method utilizing a laser sensor is adopted to practice a specific operation by making a robot move along an operation line such as a welding line. In such a conventional tracking method, a robot is controlled by detecting a relative position of a characteristic part of a workpiece or a distance to the characteristic part by using a laser sensor, and by correcting an instruction path of the robot which determines the movement of the robot.
A robot controlling method has not yet been realized which can control an attitude of a robot in association with a specified surface of a workpiece or a direction of an operating line. Namely, in the conventional methods, the attitude of a robot whose position is being corrected by a laser sensor is determined by a method for dividing and distributing attitudes at the adjacent two instruction points or by a method for maintaining the attitude of the robot constant irrespective of any changes in the workpiece side affected by the movement of the robot.
According to these conventional methods, it is possible to correct the position of robot by using a laser sensor but impossible to control the attitude of a robot by detecting the change in the workpiece side by a laser sensor. Therefore, when the change of a relative shape of the workpiece is large, it is necessary to determine a lot of instruction points and to instruct the attitudes of a robot all at every instruction point. This is a serious factor to decrease the efficiency of operation.